Axions are particles invoked to resolve the strong CP violation problem . Without these particles, the level of CP violation seen in the decay would give rise to a neutron electric dipole moment in excess of the limits already established. The allowable mass range for the axion is constrained by astrophysical arguments to to .
WIMPs are naturally predicted in supersymmetry theories in which a higher level symmetry is obtained in the particle families by introducing new particles to match each of the known particles. In the so-called minimal supersymmetry models (MSSM), the lightest supersymmetric particle (LSP) is likely to be a neutralino , which is a mixture of two neutral gauginos and two neutral higgsinos :. The mass range for neutralinos is , where the lower limit comes from accelerator data from LEP .
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